Filter device

ABSTRACT

The invention relates to a filter device, in particular for fluids polluted with admixtures of water, such as diesel oil, comprising a filter housing ( 1 ) which has fluid connections in the form of a fluid inlet ( 51 ) and a fluid outlet and in which at least one filter element ( 9 ) can be received. During the filtering process, fluid can flow through the filter medium ( 11 ) of the filter element from the unfiltered side ( 13 ) to the filtered side ( 19 ) of the filter medium, which surrounds an inner filter cavity ( 17 ). On one side of the filter medium ( 11 ), a water-separating device ( 26 ) and a separating region ( 27 ) for separated water are present, and the filter element ( 9 ) has a passage ( 43 ) that forms a fluid connection to the filter cavity ( 17 ) and at least one water opening ( 47 ) that is open toward the separating region ( 27 ). The filter element can be fixed to an element receptacle ( 29 ) of the filter housing ( 1 ) and can be connected to a water collecting chamber ( 33 ). The filter device is characterised in that an adapter part ( 49 ) is provided at least as part of a fluid-conducting system, in which fluid paths separated from each other are formed, of which the first fluid path ( 59, 67, 61 ) leads from a fluid connection ( 51 ) of the housing ( 1 ) via the passage ( 43 ) to the inner filter cavity ( 17 ) of the filter element ( 9 ) and the second fluid path ( 69 ) connects the respective water opening ( 47 ) to the water collecting chamber ( 33 ).

The invention relates to a filter device that is intended in particular for fluids, such as diesel oil, contaminated with water impurities, and that comprises a filter housing, which has fluid connections in the form of a fluid inlet and a fluid outlet and can accommodate at least one filter element. During the filtration process, the fluid can flow through the filter medium of the filter element from the unfiltered side to the filtered side of the filter medium surrounding an inner filter cavity. In this case, one side of the filter medium has a water separation device and a separation zone for separated water; and the filter element has a passage forming a fluid connection to the filter cavity, and at least one water passage that is open in the direction of the separation space. The filter element can be secured on an element retainer of the filter housing and can be connected to a water collecting space.

Filter devices of the aforementioned type are known from the prior art. Such filter devices are used, for example, in fuel systems for internal combustion engines in order to protect sensitive components, in particular the injection systems, against degradation due to the water content entrained in the fuel. In this case, separation of the water content entrained in the fuel can be brought about by a coagulation process during which water droplets are formed on the filter medium, and these water droplets can flow from the separation space, formed in the filter element, to the water collecting space.

Owing to the high requirements to be imposed on the operational reliability of such filter devices, the design configuration of the fluid connections between the ports of the housing and the filter element as well as between the filter element and the water collecting space has to be complex. Since it is very likely that such devices will be produced in large quantities, the production costs are a significant factor.

Based on the above-described problem, the object of the present invention is to provide a filter device of the aforementioned type that is economical and efficient to produce.

The present invention achieves this object with a filter device having the features specified in claim 1 in its entirety.

According to the characterizing part of claim 1, an important feature of the invention lies in the fact that an adapter part, which can be accommodated preferably at the element retainer of the filter housing, is provided as the fluid-conducting device, which provides the pertinent fluid connections, in that the adapter part forms fluid paths, which are separated from each other and of which the first fluid path leads from a fluid connection by way of the passage to the inner filter cavity of the filter element; and the second fluid path connects the respective water passage at the filter element to the water collecting space. Since it is not absolutely mandatory that the fluid-conducting device be a component of the filter element, just the filter element alone can be easily manufactured in a simple design and, can, therefore, be produced at a low cost without the cost-intensive fluid-conducting elements. In contrast to those fluid-conducting elements that belong to the filter element—such as the fluid-conducting elements that are implemented, for example, by means of an intricately designed end cap of the filter element—and that have to be changed together with the used filter element when changing the filter element, the present invention provides that the fluid-conducting device can stay in the form of the adapter part, to be found at the element retainer, in the filter housing, so that an additional cost advantage is gained. Another advantage lies in the fact that adapter parts of uniform construction can be used for filter elements that can be secured on the element retainer even though said filter elements may vary in design and/or meet different specifications, so that the adapter parts can be manufactured identically in large quantities and, therefore, economically and efficiently. However, the respective adapter part, designed preferably as a clip part, can be securely fitted on the underside of the respective filter element, for example, on the lower end cap of the filter element.

In the exemplary embodiments, in which the lower end of the filter element has an end cap, which has the passage leading into the filter cavity, and the at least one water passage, the end cap can be brought into a sealed fluid communication with the adapter part. Such a feature can be easily implemented if, for example, on the one hand, the end cap can be secured on the element retainer in order to form a seal; and, on the other hand, the adapter part is sealed off at the element retainer.

In the exemplary embodiments, in which during the filtration operation the fluid can flow through the filter medium of the filter element from the outer unfiltered side to the inner filter cavity forming the filtered side of the filter medium, the arrangement is configured preferably in such a way that the first fluid path of the adapter part connects the passage of the end cap that leads into the filter cavity to the fluid outlet of the housing; and the second fluid path of the adapter part connects the respective water passage of the end cap to the water collecting space.

In especially preferred exemplary embodiments, the element retainer has a pipe connector, which forms the connection between the main part of the housing that accommodates the filter element and the water collecting space that is located underneath said main part, with the adapter part having a sleeve body that can be accommodated in the pipe connector. Hence, it is very easy to implement the fluid connection between the end cap and the adapter part, in that the end cap is sealed on the exterior of the pipe connector of the element retainer; and, inside this pipe connector, the adapter part forms the separated fluid paths for the separated water and the fluid that is to be cleaned. A seal on the interior of the pipe connector is also possible.

In especially preferred exemplary embodiments, the arrangement is configured in such a way that the sleeve body of the adapter part has an inner tube having an open end that forms a connecting piece, which extends in a sealing manner through the passage of the end cap into the filter cavity of the filter element located in the functional position and forms a subsection of the first fluid path.

According to one advantageous design, an intermediate space, forming a water channel, can be provided between the exterior of the inner tube and the interior of the sleeve body. In this context, the intermediate space forms the second fluid path, by way of which water, issuing from the respective water passage of the end cap, flows through the open lower end of the sleeve body into the water collecting space.

With respect to routing the first fluid path, the arrangement can be configured in such an advantageous manner that the annular sections projecting radially beyond the exterior of the sleeve body come into sealing contact with the interior of the pipe connector of the element retainer and are arranged at an axial distance from one another, so that between them an annulus is formed on the exterior of the sleeve body and on the interior of the pipe connector; and this annulus is in communication, as the outlet section of the first fluid path, with the fluid outlet of the housing.

For the rest of the way of the first fluid path, the adapter part can be configured in such an advantageous manner that a cross duct branches off in the region of the lower end of the inner tube of the adapter part that faces away from the connecting piece; and this cross duct empties into the annulus and continues the first fluid path through the inner tube and its connecting piece.

In order to secure the end cap of the filter element in a sealed manner on the element retainer, the pertinent end cap can have a bearing ring, which projects axially downward from the end cap bottom and engages with the facing end of the pipe connector of the element retainer to form a seal.

In especially preferred exemplary embodiments, the respective end cap of the filter element has an annular body that surrounds the passage and projects axially from the end cap bottom into the separation space; and the interior of this annular body has at least one water passage.

If the end cap has a second axially projecting annular body, which surrounds the passage and is arranged radially inside the first annular body, then this first annular body can form a support for a hydrophobic screen belonging to the separation device. This hydrophobic screen rests against the exterior of the second annular body. When the filter element is located in the functional position, the connecting piece at the end of the inner tube of the adapter part can extend into the annular body and can be sealed off from its interior.

The end cap bottom can have a ring-shaped bottom depression in the region located between the first and second pair of annular bodies, so that at least one breakthrough is provided as the water passage at the lowest point of the separation space that is formed in this way.

In the case of a seal that is formed between the end cap bottom and the pipe connector of the element retainer when the filter element is secured on the element retainer, it is possible to dispense with a sealing device that seals off the outer circumferential edge of the end cap from the inner wall of the filter housing, so that a seal having a correspondingly large diameter can be eliminated; and, instead, the seal between the unfiltered side and the filtered side is implemented with a significantly smaller sealing diameter, so that less physical effort is required for assembly and, as a result, the filter elements are easier to install and remove.

The invention is explained in detail below by means of the exemplary embodiments depicted in the drawings. Referring to the drawings:

FIG. 1 is a longitudinal sectional view of an exemplary embodiment of the inventive filter device in the form of a fuel filter;

FIG. 2 is an enlarged perspective oblique view of just the region (cut in the longitudinal direction) of the exemplary embodiment that is adjacent to the element retainer and is depicted in FIG. 1; and

FIG. 3 is a view similar to the one from FIG. 2, showing a modified exemplary embodiment.

The invention is explained below, using the example of a fuel filter, which is provided in a fuel supply system (not illustrated) of an internal combustion engine for cleaning diesel oil, which is contaminated with certain water impurities. The invention also lends itself just as well to other kinds of fluids.

The device has a filter housing 1 comprising a main part 3 in the form of a hollow cylinder and a bottom part 5 that is located on the underside of the main part. At the upper end, a housing cover 7 is screwed to the main part 3; and this housing cover can be removed for the purpose of installing and removing a filter element 9. The filter medium 11 of the filter element 9, which is to be accommodated in the filter housing 1, is formed by a filter mat, forming a hollow cylinder. Between the exterior of the filter medium 11 and the inner wall of the housing 1, there is an intermediate space, which forms the unfiltered side 13 during the filtration operation. The fuel that is to be cleaned is fed to the unfiltered side 13 by way of a fluid connection of the housing 1. However, this fluid connection cannot be seen in the drawing because of the rotational position of the filter housing. During the filtration operation, the fuel flows through the filter medium 11 from the outer unfiltered side 13 inward to an inner filter cavity 17 that forms the filtered side 19.

The ends of the filter element have in the conventional manner end caps 21 and 23, which form enclosures for the filter medium 11 and a fluid-permeable support tube 26, which rests against the interior of said filter medium. A hydrophobic screen 25, which surrounds the inner filter cavity 17 in the form of a tube, is located at a radial distance from the support tube 26. In order to effect water separation, such fuel filters use a filter medium 11 that acts in a coagulating manner on the water entrained by the fuel, so that water precipitates out in droplet form; and this water remains and sinks down in the separation space 27, forming a separation zone between the hydrophobic screen 25 and the support tube 26, because the screen is impermeable to coagulated water droplets.

The filter element 9 is secured with its lower end cap 23 on an element retainer 29 that is rigidly mounted in the housing. This element retainer has the form of a pipe connector 31, which forms the connection between the main part 3 of the housing 1 that accommodates the filter element 9 and the water collecting space 33 that is located underneath said main part. In order to secure the filter element 9 on the element retainer 29, the lower end cap 23 has a bearing ring 35, which extends axially downward from the end cap bottom 37, which forms the support for the ends of the filter medium 11 and the support tube 26, and engages with the upper edge region of the pipe connector 31 of the element retainer 29 when the filter element 9 is in the functional position, so that a sealing element, sitting in the bearing ring 35, forms the seal. In the first exemplary embodiment shown in FIGS. 1 and 2, the bearing ring 35 surrounds two annular bodies 39 and 41 that are arranged at a radial distance from one another. Said annular bodies project axially into the interior of the filter element 9 away from the end cap bottom 37 and surround the passage 43 leading into the inner filter cavity 17. The support tube 26 rests against the exterior of the radially outer annular body 39. The hydrophobic screen 25 rests against the exterior of the annular body 41 that is disposed further on the inside. In the intermediate space between the annular bodies 39 and 41, the end cap bottom 37 forms a bottom depression 45 in the form of an annular trough. This bottom depression forms the lowest point of the separation space 27 and is perforated by breakthroughs that form the water passages 47.

A fluid-conducting device is provided for the interaction with the end cap 23 and the pipe connector 31 of the element retainer 29. This fluid-conducting device is formed by an adapter part 49, which has, as a one-piece molded part made of plastic, the form of a rotational body that is accommodated in the pipe connector 31 of the element retainer 29. In its function as the fluid-conducting device, the adapter part 49 forms fluid paths that are separated from one another. Of these fluid paths, the first fluid path leads from a fluid connection of the housing 1, which forms a fluid inlet 51 in the present example, through the passage 43 of the end cap 23 to the filter cavity 17; and the second fluid path connects the separation space 27 of the filter element 9 to the water collecting space 33.

FIGS. 2 and 3 show the best that the adapter part 49 has a sleeve body 53, on the exterior of which there are two radially projecting annular sections 55 and 57 that make sealing contact with the interior of the pipe connector 31. The annular sections 55, 57 are set at an axial distance from one another, so that between them an annulus 59 is formed that is connected, as the subsection of the first fluid path, to the fluid input 51 by means of a fluid connection that is not visible in the drawing. Inside the sleeve body 53, there is in coaxial arrangement an inner tube 61, which extends in a sealing manner with its upper open end 63 into the annular body 41, which forms the passage 43 and is a part of the end cap 23, which is in the functional position. In the region of the closed lower end 65 of the inner tube 61, a cross duct 67 branches off from said lower end of the inner tube. This cross duct empties into the annulus 59 and, thus, completes the first fluid path through the inner tube 61 into the filter cavity 17. The exterior of the inner tube 61 is at a distance from the interior of the sleeve body 53, so that a water channel 69 is formed, into which water enters from the separation space 27 by way of the water passages 47 of the end cap 23 and flows out through the lower open end 71 of the sleeve body 53 to the water collecting space 33. In this way, the water channel 59 in the adapter part 49 forms the second fluid path.

The exemplary embodiment from FIG. 3 differs from the above-described example only in its simplified design of the end cap 23 of the filter element 9, whereas the filter housing and the element retainer 29 are identical in construction; and, furthermore, the same adapter part 49 can be used as in the first exemplary embodiment. As in the previous example, the end cap 23 is secured on the pipe connector 31 of the element retainer 29 by means of the bearing ring 35, which engages with the pipe connector 31 at the upper edge. However, in contrast to the previous example, the end cap bottom 37 does not exhibit the trough-like bottom depression 45 and, connected to it, the inner annular body 41. Instead, the upper end 63 of the inner tube 61 of the adapter part 49 engages directly with the hydrophobic screen 25 of the filter element; and the opening, surrounded by the annular body 39, forms, with the entire intermediate space between the hydrophobic screen 25, the water passage 47, which connects the separation space 27 to the water channel 69 in the adapter part 49.

In both exemplary embodiments, the sealing between the bearing ring 35 of the end cap 23 and the pipe connector 31 of the element retainer 29 as well as of the sleeve body 53 of the adapter part 49 relative to the pipe connector 31 and similarly the sealing of the inner tube 61 of the adapter part 41 at the passage 43 to the filter cavity 17 is formed in each instance by an O-ring 75. Unlike conventional filter devices, it is not necessary to seal off the outer periphery of the end cap 23 from the interior of the filter housing 1 when the unfiltered side 13 is sealed off from the filtered side 19 by means of the bearing ring 35 of the end cap relative to the pipe connector 31. Moreover, the respective adapter part 49 is secured in position by means of the at least partially conical inner wall of the respective receptacle 31 with the adjoining cylindrical sections, on which the O-ring 75 of the adapter part 49 is supported. The flow direction of the device can also be reversed with a few structural adaptations. The water separation device 26 can also be constructed as a part of the element retainer 29 in an embodiment that is not illustrated herein. 

1. A filter device that is intended in particular for fluids, such as diesel oil, contaminated with water impurities, and that comprises a filter housing (1), which has fluid connections in the form of a fluid inlet (51) and a fluid outlet and can accommodate at least one filter element (9); and during the filtration process, the fluid can flow through the filter medium (11) of the filter element from the unfiltered side (13) to the filtered side (19) of the filter medium surrounding an inner filter cavity (17), wherein one side of the filter medium (11) has a water separation device (26) and a separation zone (27) for separated water; and the filter element (9) has a passage (43) forming a fluid connection to the filter cavity (17), and at least one water passage (47) that is open in the direction of the separation zone (27); and the filter element can be secured on an element retainer (29) of the filter housing (1) and can be connected to a water collecting space (33), characterized in that an adapter part (49) is provided at least as a part of a fluid-conducting device, in which fluid paths, which are separated from each other, are formed; and of these fluid paths, the first fluid path (59, 67, 61) leads from a fluid connection (51) of the housing (1) by way of the passage (43) to the inner filter cavity (17) of the filter element (9); and the second fluid path (69) connects the respective water passage (47) to the water collecting space (33).
 2. The filter device according to claim 1, characterized in that the water separation device (26) and its water passage (47), which is open in the direction of the separation zone (27), are components of the filter element (9); and that the adapter part (49) can be mounted on the element retainer (29).
 3. The filter device according to claim 1, characterized in that the lower end of the filter element (9) has an end cap (23), which has the passage (43) leading into the filter cavity (17), and the at least one water passage (47), and that the adapter part (49) can be brought into a sealed fluid communication with the end cap (23).
 4. The filter device according to claim 1, characterized in that the water collecting space (33) is connected to the filter housing at the lowest point of the filter housing (1); and that the element retainer (29) of the filter housing (1) is located above the water collecting space (33).
 5. The filter device according to claim 1, characterized in that during the filtration operation the fluid can flow through the filter medium (11) of the filter element (9) from the outer unfiltered side (13) to the inner filter cavity (17) forming the filtered side (19) of the filter medium; and that the first fluid path (59, 67, 61) of the adapter part (49) connects the passage (43) of the end cap (23) that leads into the filter cavity (17) to the fluid outlet (51) of the housing (1); and the second fluid path (69) of the adapter part (49) connects the respective water passage (47) of the end cap (23) to the water collecting space (33).
 6. The filter device according to claim 1, characterized in that the element retainer (29) has a pipe connector (31), which forms the connection between the main part (3) of the housing (1) that accommodates the filter element (9) and the water collecting space (33) that is located underneath said main part; and that the adapter part (49) has a sleeve body (53) that can be accommodated in the pipe connector (31).
 7. The filter device according to claim 1, characterized in that the sleeve body (53) has an inner tube (61) having an open end (63) that forms a connecting piece, which extends in a sealing manner through the passage (43) of the end cap (23) into the filter cavity (17) of the filter element (9) located in the functional position and forms a subsection of the first fluid path.
 8. The filter device according to claim 1, characterized in that an intermediate space, forming a water channel (69), is provided between the exterior of the inner tube (61) and the interior of the sleeve body (53) of the adapter part (49); and this intermediate space forms the second fluid path, by way of which water, issuing from the respective water passage (47) of the end cap (23), flows through the open lower end (71) of the sleeve body (53) into the water collecting space (33).
 9. The filter device according to claim 1, characterized in that the annular sections (55, 57) projecting radially beyond the exterior of the sleeve body (53) come into sealing contact with the interior of the pipe connector (31) of the element retainer (29) and are arranged at an axial distance from one another, so that between them an annulus (59) is formed on the exterior of the sleeve body (53) and on the interior of the pipe connector (31); and this annulus is in communication with the fluid outlet (51) of the housing (1) as the outlet section of the first fluid path.
 10. The filter device according to claim 1, characterized in that a cross duct (67) branches off in the region of the lower end (65) of the inner tube (61) of the adapter part (49) that faces away from the connecting piece; and this cross duct empties into the annulus (59) and continues the first fluid path through the inner tube (61) and its connecting piece.
 11. The filter device according to claim 1, characterized in that for securing on the element retainer (29), the lower end cap (23) of the filter element (9) has a bearing ring (35), which projects axially downward from the end cap bottom (37) and engages with the facing end of the pipe connector (31) of the element retainer (29) to form a seal.
 12. The filter device according claim 1, characterized in that the lower end cap (23) of the filter element (9) has an annular body (39) that surrounds the passage (43) and projects axially from the end cap bottom (37) into the separation zone (27); and the interior of this annular body has at least one water passage (47).
 13. The filter device according claim 1, characterized in that a second axially projecting annular body (41), which surrounds the passage (43) of the end cap (23), is arranged radially inside the first annular body (39); and that a hydrophobic screen, belonging to the separation device, rests against the exterior of the second annular body (41).
 14. The filter device according to claim 1, characterized in that the end cap bottom (37) has a ring-shaped bottom depression (45) in the region located between the first and the second annular body (39, 41); and that at least one breakthrough (47) is designed, as the water passage, in this bottom depression. 